Heatwave Pleases Northwest Vintners
Record temperatures hasten harvest, depress fungus, especially west of Cascades
The University of Washington Probability Forecast looks sizzling throughout the Pacific Northwest.
Everson, Wash. -- Northwest vineyards are catching up after a cool spring with the help of a massive high-pressure system that's driven temperatures above 100ºF in many parts of a region known for more temperate conditions. The hardest-hit areas lie west of the Cascade mountain range, where a heat wave that began last weekend has been breaking temperature records daily.
Vineyards in British Columbia's Fraser Valley and the Puget Sound AVA of Washington state have been reporting temperatures above 100ºF this week (80ºF is closer to historical averages), while temperatures in Portland and the Rogue Valley of Oregon broke records set in 1998 and 2003, respectively, when the mercury spiked above 105ºF.
"We're used to about 1,600, 1,700 heat units in any given year, and we're already above 1,800 -- moving towards 2,300 -- if things continue," said David Traynor, cellar master at Mount Baker Vineyards in Everson, Wash.
Thermometers at the winery's 6.5-acre vineyard east of Bellingham hit 105ºF on Wednesday, hotter than most locals can remember. The temperatures are more typical of the Eastern Washington vineyards that supply Mt. Baker with most of its fruit, and they are taking their toll on the cool-climate grapes in its home vineyard.
"The Siegerebbe so far looks fine, but the Madeleine Angevine is starting to look like it's getting affected pretty harshly," Traynor told Wines & Vines. The good news, however, is that the grapes are maturing rapidly, and harvest could begin as early as late August if the heat breaks and the vines get some rain. "I'm hoping the hot weather slows down a little bit," Traynor said. "That will allow the plants to recover a little."
Growers in Oregon also expect the heat to allow for an early harvest, with wineries in both the Rogue and Willamette valleys reporting grapes maturing a week and a half ahead of normal.
Hans Ahl, vineyard manager at Bridgeview Vineyard in Cave Junction, Ore., said temperatures reached 110ºF in Bridgeview's Rogue Valley AVA properties this week, and the fruit is looking good.
While other local growers use overhead sprayers to cool down their vines, Bridgeview employs drip irrigation, and the vines have been bearing up. Water is in good supply -- a luxury not enjoyed everywhere.
Vineyards in the Willamette Valley are typically dry-farmed, which has prompted Jason Tosch of Anne Amie Vineyards in Carlton to address hot weather through canopy management. Temperatures at Anne Amie hit 106º F this week, while some pockets of the Willamette reached 111ºF.
"It seems like we've been getting 100º spells for the last three or four years, so what I've gone to, just as a standard practice, is this hedging management scenario where we just let the canopy hang on," he said. "My belief is that that bigger canopy helps the plant create its own little humid, cooler microclimate down in the fruiting zone." An initial thinning of the canopy in July will be followed by a second pass at the start of August, or once the current heat wave moderates.
Speaking after a walk through the vineyard, Tosch said the strategy seemed to be working, with no sunburn apparent on the berries. The vines weren't showing signs of drought-stress either, which Tosch attributed to the use of 3309 and 101-14 rootstock.
While the hot temperatures may be favoring the developing clusters, many Willamette wineries are also cheering what isn't growing in the current heat wave: fungi.
"The only thing that's not growing is mildew, which is beautiful because we don't have to spray," Tosch said, noting that he hasn't sprayed for more than two weeks, though that might change if temperatures drop below 90º, and the rain forecast for early next week arrives.
Otherwise, Tosch is pleased with the progress of the season, as is Laura Volkman, who is expecting an early harvest and fine vintage at Laura Volkman Vineyards above Newberg, Ore. "I think it's going to be a beautiful vintage," she said. "But there's no telling what's going to happen between now and then. It's two months away, so we'll just keep our fingers crossed that it gets back into the 80ºs and stays there."